Sabrina had some pen collection.
19 of them were black and the rest were gold. She gave away 115 of the gold pens and 50% of the black pens. She then had
23 of her pen collection left. How many pens did Sabrina give away?
| |
Black |
Gold |
Total |
Total |
Before
|
1x1 =
1 u |
8x1 =
8 u |
9x1 =
9 u |
3x3 =
9 u |
Change
|
- 0.5x1 =
- 0.5 u |
- 115 |
|
- 1x3 =
- 3 u |
After
|
0.5x1 =
0.5 u |
8 u - 115 |
|
2x3 =
6 u |
The total number of pens that Sabrina had at first is repeated. Make the total number of pens at first the same. LCM 9 and 3 is 9.
Number of black pens that Sabrina gave away
= 50% x 1 u
=
50100 x 1 u
= 0.5 u
0.5 u - 115 = 3 u
3 u - 0.5 u = 115
2.5 u = 115
1 u = 115 ÷ 2.5 = 46
Number of pens that Sabrina gave away
= 3 u
= 3 x 46
= 138
Answer(s): 138
